Canberra, Dec 15 (IANS): Australia has increased striking key Islamic State (IS) targets in Syria and Iraq following changes to its war crimes legislation, a senior air force officer said on Thursday.

In June, the Australian government modified its war crimes bill to allow servicemen to engage in wider range of hostile terrorist targets without fear of prosecution, Xinhua news reported.

On Thursday, the air force officer told media that since the changes were implemented, Australian bombers were recording a "weapons release rate" of 61 per cent, up from 20 per cent earlier in 2016.

"Previously we would have rejected targets because they fell outside of our rules of engagement and we would have picked up other targets," the officer said.

"Now we can actually pick those more difficult targets as well," he added.

The officer said since the laws were amended to relieve pilots and other service men and women of the risk of prosecution, the campaign against IS turned much more effective.

He said that pilots were now able to go after harder targets including convoys which carry pay for soldiers, as well as communications centres, bomb-making warehouses and production factories.

"(That) is really our forte in terms of the skill set we have both in our air crew and our aircraft capabilities," the officer added.

"Sometimes the harder targets are in more complex areas where there are increased collateral damage concerns," he said.